Document FR-2-358 897 discloses a dynamic diffuser which comprises, in a housing provided with air evacuation orifices, a fan enabling a flow of air to be passed over the medium supporting the substance to be vaporized.
In a preferred embodiment described in that prior document, the dynamic diffuser includes a removable cartridge which is constituted firstly by a round battery for electrically powering a motor which drives the fan, and secondly an annular receptacle mounted around said round battery and containing the material supporting the substance to be vaporized. Said annular receptacle is pierced in its two plane faces by orifices for passing air. The cylindrical cartridge is placed coaxially relative to the axis of rotation of the fan and it faces the fan so that the air flow created by rotation of the fan penetrates into the receptacle, travels over the surface of the medium supporting the substance to be vaporized, and escapes from the housing. In that case, the medium supporting the substance to be vaporized is a porous strip impregnated with said substance.
In the field of perfume, dynamic diffusers of that type are also known in which the perfume element is in the state of a gel or of a solid block. The flow of air coming from a fan and travelling over the surface of the gel or the block accelerates natural diffusion of the perfume.
As observed by the Applicant, such known dynamic diffusers suffer from a drawback which consists in the concentration of the perfumed substance in air diminishing progressively over time. Thus, in a room containing the diffuser in question, a user does not obtain the same perfume sensation throughout the time during which the diffuser is in use.
If the substance to be vaporized is an insecticide, then the effectiveness of the diffuser decreases over time.
Proposals have already been made in document GB-1-454 040 for a diffuser in which the naturally diffusing substance is in the liquid state. The diffuser in question includes a receptacle whose bottom is pierced by an orifice which leads to a chamber containing an absorbent material. The liquid passes progressively into the absorbent material under gravity and under capillarity. The chamber is itself provided with lateral openings, and a fan is disposed facing said openings so that a flow of air passes through the chamber and the absorbent pad, and becomes charged with the naturally diffusing substance.
The Applicant has found that that diffuser suffers from drawbacks. When the absorbent material is saturated, the liquid substance drips out from the chamber and is lost. The flow of air through the absorbent material suffers a large loss of head, thereby requiring greater power for the fan-driving motor for a given air flow. The chamber containing the absorbent material is bulky.